The present invention relates to the use of a pre-alloyed powder containing iron as binder in the manufacture of diamond tools by hot sintering.
In the manufacture of diamond tools by hot sintering, with or without pressure, of an intimate mixture of diamond and of binder, use is made, for the binder, that is to say the material forming the matrix of the tool at the end of the sintering operation, either of fine cobalt powders (1-6 xcexcm) or of mixtures of fine powders, such as a mixture of fine cobalt, nickel and iron powders, or coarse pre-alloyed powders (less than 44 xcexcm), such as a steel powder obtained by atomization.
The use of a fine cobalt powder has very good results from a technical standpoint; its only drawback stems from the high price of the powder.
Using mixtures of fine powders, matrices are obtained whose hardness and, consequently, the wear resistance, are relatively low.
The use of coarse pre-alloyed powders requires a sintering temperature of about 1100-1300xc2x0 C., at which temperature degradation of the diamond, called graphitization, becomes appreciable.